THE CRETACEOUS SYSTEM. 



731 



rhinoceros, and crested with horns, such a creature must have been the Iguanadon ! 

 Nor were the inhabitants of the waters much less wonderful ; witness the Plesiosaurus,' 

 which only required wings to be a flying dragon." The name of Mantell will ever be 

 associated with the Wealden beds, as that of Cuvier is with the Paris basin, Murchison 

 with Silurian strata, and Lyell with the Tertiary deposits. 



CHAPTER IX. 



CRETACEOUS SYSTEM. 



HE scheme of deposits included in this 

 system, ranging from a thousand to twelve 

 hundred feet in thickness, receives its name 

 from the common mineral, chalk (creta\ the 

 most prominent member of the group. This 

 is one of the best known and clearly defined 

 formations of the globe, resting upon wealden 

 strata in Kent and Sussex, upon oolitic 

 rocks in other places, and, where these are 

 wanting, upon the lias. In England, the 

 cretaceous system extends over a consider- 

 able part of the south-eastern and eastern 

 counties, overlooks the waters of the Chan- 

 nel at Brighton, and the German Ocean at 

 Flamborough Head in Yorkshire, though it 

 is not continuous through the interval be- 

 tween these two points. From the latter headland, it travels inland in a large curve to the 

 H umber, reappears on the Lincolnshire side of the river, and proceeds in a straight broad 

 band to Spilsby, where its course is interrupted. South of the estuary of the Wash, it oc- 

 curs in a detached curved tract in Norfolk. At Thetford, in that county, the chalk becomes 

 continuous, from thence ranging southward through the counties of Cambridge^ Bedford, 

 Oxford, and Wilts, to the sea in Dorset, andj proceeding eastward from Wiltshire through 

 the south-eastern counties^ it extends to the coast of Kent at Dover. The cretaceous 

 system makes no appearance iii Wales or Scotland, but it occurs in the north of Ireland. 

 On the continent, it is largely developed in France, bordering the Channel from Boulogne 

 to Havre, and surrounding in a broad ring the tertiary basin of Paris. The members of 

 the formation appear in various parts of Germany, in the Alps, the Carpathians, and 

 Pyrenees. In North America, it is supposed to occur abundantly on the Missouri to the 

 foot of the Rocky Mountains. But in Ireland, the chalk occurs under circumstances which 

 nowhere belong to it in England, for there> in the county of Antrim, it has been broken 

 through and overlain, by that magnificent outburst of basalt which built up the Giants' 

 Causeway. Here, the metamorphic change induced by the action of intense heat is mani- 

 fest, in the conversion of the chalk into a crystalline marble, while the lias has been 

 changed into a kind of flinty slate, and the coal shales and red sandstone have been 

 variously hardened. In some foreign localities cretaceous strata have likewise been 



